Returns a copy of this String object converted to uppercase using the casing rules of the invariant culture.
Assembly: mscorlib (in mscorlib.dll)
The invariant culture represents a culture that is culture-insensitive. It is associated with the English language but not with a specific country or region. For more information, see Using the InvariantCulture Property.
If your application depends on the case of a string changing in a predictable way that is unaffected by the current culture, use the ToUpperInvariant method. The ToUpperInvariant method is equivalent to ToUpper(CultureInfo.InvariantCulture). The method is recommended when a collection of strings must appear in a predictable order in a user interface control.
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This method does not modify the value of the current instance. Instead, it returns a new string in which all characters in the current instance are converted to uppercase. |
Security Considerations
The casing operation that results from calling the ToLower method takes the casing conventions of the current culture into account. If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant method. This produces the same result in every culture (unlike the ToLower method) and performs more efficiently.
The following example defines a string array that contains a single word in a number of languages. The ToUpperInvariant method is used to populate the elements of a parallel array with the case-insensitive version of each word. The Array
Imports System.IO
Module Example
Public Sub Main()
Dim words() As String = { "Tuesday", "Salı", "Вторник", "Mardi", _
"Τρίτη", "Martes", "יום שלישי", _
"الثلاثاء", "วันอังคาร" }
Dim sw As New StreamWriter(".\output.txt")
' Display array in unsorted order.
For Each word As String In words
sw.WriteLine(word)
Next
sw.WriteLine()
' Create parallel array of words by calling ToUpperInvariant.
Dim upperWords(words.Length - 1) As String
For ctr As Integer = words.GetLowerBound(0) To words.GetUpperBound(0)
upperWords(ctr) = words(ctr).ToUpperInvariant()
Next
' Sort the words array based on the order of upperWords.
Array.Sort(upperWords, words, StringComparer.InvariantCulture)
' Display the sorted array.
For Each word As String In words
sw.WriteLine(word)
Next
sw.Close()
End Sub
End Module
' The example produces the following output:
' Tuesday
' Salı
' Вторник
' Mardi
' Τρίτη
' Martes
' יום שלישי
' الثلاثاء
' วันอังคาร
'
' Mardi
' Martes
' Salı
' Tuesday
' Τρίτη
' Вторник
' יום שלישי
' الثلاثاء
' วันอังคาร
using System;
using System.IO;
public class Example
{
public static void Main()
{
string[] words = { "Tuesday", "Salı", "Вторник", "Mardi",
"Τρίτη", "Martes", "יום שלישי",
"الثلاثاء", "วันอังคาร" };
StreamWriter sw = new StreamWriter(@".\output.txt");
// Display array in unsorted order.
foreach (string word in words)
sw.WriteLine(word);
sw.WriteLine();
// Create parallel array of words by calling ToUpperInvariant.
string[] upperWords = new string[words.Length];
for (int ctr = words.GetLowerBound(0); ctr <= words.GetUpperBound(0); ctr++)
upperWords[ctr] = words[ctr].ToUpperInvariant();
// Sort the words array based on the order of upperWords.
Array.Sort(upperWords, words, StringComparer.InvariantCulture);
// Display the sorted array.
foreach (string word in words)
sw.WriteLine(word);
sw.Close();
}
}
// The example produces the following output:
// Tuesday
// Salı
// Вторник
// Mardi
// Τρίτη
// Martes
// יום שלישי
// الثلاثاء
// วันอังคาร
//
// Mardi
// Martes
// Salı
// Tuesday
// Τρίτη
// Вторник
// יום שלישי
// الثلاثاء
// วันอังคาร
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.